Influence of Open Apex on Working Length Determination Using Cone-Beam Computed Tomography and Apex Locators: A Comparative In Vitro Study

OBJECTIVES: The aim of this study is to assess the effect of open apex on working length (WL) determination with aid of cone-beam computed tomography (CBCT) and electronic apex locators (EALs). METHODS: Thirty-two extracted human mandibular premolars were selected, and apical 5 mm was removed. Root canals were prepared from the apical to the coronal direction of the canal using peeso reamers up to size 5 (retrograde) to simulate open apex. The samples were analyzed by CBCT, and WL was established (CWL) by a radiologist. An endodontist prepared the access cavities, and visual working length (VWL) was recorded. The samples were embedded in a freshly mixed alginate mould up to cementoenamel junction. Each root canal length was measured with two different EALs—Root ZX mini and i Root. The measurements were repeated 3 times by using a digital caliper, and the mean was recorded by the endodontist who was blinded to the results of the CWL. The recorded data was statistically analyzed using the SPSS software. RESULTS: The results of this study showed statistically significant difference between VWL and i Root, CWL and i Root, and Root ZX mini and i Root (p < 0.05). Amongst EALs, a superior accuracy was noted for Root ZX mini than as compared to i Root. However, no statistically significant difference was seen between Root ZX mini and CWL (p > 0.05). CONCLUSION: The present study showed that CWL is as accurate and reliable as VWL which is the gold standard. Amongst EALs, Root ZX mini performed more accurately than i Root. Preexisting CBCT scans should be used as an advantage in determining WL.